Rear brake conversion

[66Paul]

I am having trouble finding replacement parts for my rear brakes and am wondering if anyone has successfully converted to later model brake calipers, such as from an XJ-6? Were any modifications required, or did they bolt in?

[Glyn Ruck]

Do you still have your original rear calipers? If so just have them re-sleeved in stainless steel & refurbished. All the other parts are available.

I had all the calipers, master & slave cylinders stainless sleeved on my car.

[66Paul]

Yes, I have the original calipers, but having trouble finding new pistons as mine are badly pitted. Understand these calipers were used only Mark X and S-Type, and use the rare pistons with retracting pins. Was hoping to find a more modern setup that would provide better stopping and be more serviceable but don't know how difficult a conversion would be.

[cass3958]

I have not done a rear conversion but the set up of the rear drive shafts and diff are similar on the E Type, S Type, 420, Mk10 XJS and XJ6 series. The difference as I see it is the S Type and 420 had a narrow back axle compared with the others but this was taken up with the drive shafts and lower wishbone being shorter. If you were to find an old XJ6 I am sure the brakes would be interchangeable but you might need more than just the calipers and discs. You might need the mounting points for the calipers as these might be different and the hand brake set up might also be different. If I was looking to do this I would find the complete back axle and subframe from a later XJ series car possibly even an XJS and then compare the two and swap over the brake parts to fit.

[JCS]

All the main wearing parts in the hand brake calliper on the classic S Type are interchangeable with the XJ 6 series 3 according to the parts lists. This is important to know in order to mount them to any alternative main callipers.

The XJ 6 series 3 rear main rear brake callipers, according to SNG Barratt parts list, are a straight bolt on conversion, part numbers AAU3378 / AAU3379. They offer these as a suggested conversion in their list. I am just about to consider this conversion as I currently have the rear end out of the car.

As an aside, the rear brake callipers will not straight swap between an S Type and at least an early E-type. The former have a horseshoe shaped calliper mounting bracket that is blocked by an axle casting lug on an E-type. These calliper mounting brackets are handed. In theory the aforementioned casting lug could be cut off an offending axle case, but not something I would recommend..

[Glyn Ruck]

Yes, I have the original calipers, but having trouble finding new pistons as mine are badly pitted. Understand these calipers were used only Mark X and S-Type, and use the rare pistons with retracting pins. Was hoping to find a more modern setup that would provide better stopping and be more serviceable but don't know how difficult a conversion would be.

Barratts can supply pistons. I fitted SS. I do not know XJ caliper fluid displacement. Be careful with single circuit brakes or you could disturb back to front braking bias.

Rear brake piston 1.PNG (316.49 KiB) Viewed 2964 times

Rear brake piston.PNG (76.98 KiB) Viewed 2964 times

Rear brake piston SS.PNG (337.57 KiB) Viewed 2964 times

[66Paul]

Thanks for the responses. I purchased new SS pistons from XKs Unlimited, however these do not have the spring retraction mechanism in the back like the originals, only a recess where they go. I have been unable to remove the retractors from the old pistons to reuse in the new pistons. How are they removed? If not removable, does anyone supply replacements, or will the pistons work without the retraction mechanism?

Paul

[Glyn Ruck]

I retained the retractors but while I have not done it I'm told that plain pistons work just fine. As shown in cheaper Barratt's replacements.